Born in 1497, the future king was the eldest son of Hkonmaing I, the longtime ruler of Onbaung–Hsipaw. His father was the only ally of King Narapati II of Ava between 1505 and 1527 when they unsuccessfully fought against Sawlon I of Mohnyin. His father later joined the Confederation, and died during or shortly after his participation in the Confederation's 1542 campaign against Toungoo Dynasty. Hkonmaing the younger succeeded the Onbaung throne.
Shortly after he became saopha, the Ava court came calling. King Thohanbwa, who was deeply unpopular with his subjects even before his military defeats against Toungoo Dynasty, had been assassinated in May 1542. The court elected Hkonmaing king in June 1542 after the leader of the court insurrection, Yan Naung, rejected the offer. Yan Naung agreed to remain in office and advise the new king for one year. The House of Mohnyin was furious. Not only did they believe the Ava throne rightfully belonged to them but they were also appalled by Thohanbwa's assassin Yan Naung remaining in office. Nevertheless, Sawlon II of Mohnyin relented since the Confederation was in the middle of a serious war with Toungoo. The Confederation leadership reluctantly accepted Hkonmaing as king of Ava in August/September 1542, and agreed to continue the war.
War with Toungoo
Hkonmaing prepared for war in the next 12 months. All seven Confederation states had agreed to contribute manpower and materiel. He was not able to persuade King Min Bin of Arakan to stay in the alliance however. In December 1543, he personally led the Confederation's armies and navies, and invaded Lower Burma. After initial successes, they were decisively driven back by February 1544. They could not stop advancing Toungoo forces which took all the way up to Pagan. It was a complete disaster for Hkonmaing. He had not only failed to retake Prome but also managed to lose all of central Burma. The Confederation leadership was unsure how to respond. They sent a small army led by Sithu Kyawhtin as a probe in late 1544, which was subsequently destroyed at Salin.
War with Mohnyin
By then, Sawlon II's patience had run out. He sent Sithu Kyawhtin with an army of 5,000 to take Ava. Sithu Kyawhtin easily took Sagaing, and attacked Ava. The arrival of the rainy season of 1545 saved the day for Hkonmaing. But his territory was now badly splintered: the Mohnyin-controlled west of the Irrawaddy, and Hsipaw/Onbaung-controlled eastern half. He died during the rainy season c. September 1545. He was 48.
